This document was produced by MAFF as a specific response to the FMD outbreak in the UK in 2001 and was made available on their website. Risk Assessments and specific recommendations related to the conditions in the field at the time and should be viewed in this context as they may not be applicable to outbreaks occuring under different circumstances.
Foot and mouth disease
26 March 2001

MAFF: Veterinary Risk Assessment No.6: What is the risk of causing new outbreaks of FMD by moving sheep directly from "farm A" (on which animals have been exposed to the risk of infection by proximity to an infected premises, or in some other way) to an alternative place of slaughter, and from there to a further place for disposal?

1. SUMMARY OF MAJOR RISK FACTORS IDENTIFIED IN FULL ASSESSMENT

Moving livestock during an FMD outbreak increases the risk of spreading infection to premises that were previously uninfected, as does moving carcases of potentially infected animals. The risk assessment is considered in three parts; Movement from farm of origin to place of slaughter; at the place of slaughter; and disposal after slaughter.

• failure to detect FMD infection at premises of origin (farm A)
• failure to take account of recent history of animal transport vehicle and equipment
• lack of awareness of appropriate hygienic precautions
• failure to disinfect vehicles and equipment especially externally
• failure to quarantine personnel following suspected contact with FMDV
• failure to minimise distance, time travelled, and stopping points on route
• movement of livestock or vehicles from infected areas to apparently unaffected areas
• close proximity of route/journey to other livestock premises

• failure to detect FMD infection at premises of origin (farm A)

• close proximity of lairage and abattoir to other livestock premises
• failure to minimise time sheep spend in lairage prior to slaughter
• failure to use all-out batch system at lairage and abattoir
• development of clinical FMD at lairage
• failure to take adequate precautions if clinical FMD has been detected at lairage
• failure to disinfect lairage and all equipment between successive batches of animals to be slaughtered
• failure to utilise dedicated personnel, appropriate hygiene and quarantine measures
• failure to minimise aerosol production and release of body fluids at slaughter
• failure in perimeter security of lairage and abattoir
• failure to ensure appropriate adequate containment of lairage and abattoir (with respect to both the virus and small scavenging animals)
• failure to ensure adequate and appropriate lairage (e.g. bedding, milk from any lactating sheep) and abattoir waste disposal methods, including the use of slurry, disinfectant, leakproof transport and siting of waste disposal away from susceptible livestock
• failure to disinfect delivery vehicle, equipment and personnel before they leave the abattoir

• close proximity of lairage and abattoir to other livestock premises
• failure to minimise time sheep spend in lairage prior to slaughter
• development of clinical FMD at lairage

• failure to disinfect carcases after slaughter and before movement
• method of loading, particularly dismemberment and rough handling
• failure to disinfect vehicle externally
• failure to provide residual disinfecting environment in vehicle during journey
• failure to use leakproof vehicle or container (drains may be a particular problem)
• failure to minimise distance, time travelled and stopping points on route
• failure to plan route to avoid exposure of susceptible animals
• failure to contain virus at destination
• failure of the disposal technology
• failure to site disposal plant away from susceptible animals
• lack of awareness of appropriate hygiene precautions

• failure to disinfect carcases
• failure to disinfect vehicle externally
• failure to provide residual disinfecting environment in vehicle during journey
• failure to use leakproof vehicle or container (drains may be a particular problem)

• Sheep may be slaughtered on site and their carcases
• burned or buried on site
• buried at a licensed wastetip
• sent to be rendered
• Risk assessments of procedures in which sheep are killed on site and their carcases moved elsewhere for rendering or burial, have been made, and conditions suggested which would make any of these options an acceptable risk. (Veterinary Risk Assessments no.2).
• Alternatively, sheep may be sent alive to an abattoir for slaughter, after which the carcases and by-products may be salvaged or destroyed.
• The major risk factors that have been identified can be managed by:
• ensuring that the vehicle and driver are clean and disinfected before entering the premises to collect the sheep; cleaned and disinfected externally before leaving the premises, and cleaned and disinfected inside and out, under official superivision, immediately after unloading at and before leaving the slaughterhouse.
• carrying out a veterinary inspection of all susceptible livestock on the premises immediately before sheep are loaded into the vehicle that will transport them to the slaughterhouse.
• licensing only to a slaughterhouse in the same or in a higher risk area (e.g. farm in lower risk Controlled Area to slaughterhouse in higher risk Controlled Area is permissible: the converse is not).
• licensing by most direct route to nearest suitable slaughterhouse
• using only dedicated slaughterhouse where no other animals are currently killed.
• requiring slaughter within 24 hours of delivery.
• controlling disposal of carcases and all by-products from the slaughterhouse.
• Some risk management options may be unachievable in particular areas, at least initially. The most obvious is the recommendation that movement of live sheep be conditional on veterinary inspection before loading, since the veterinary manpower to achieve this is simply not available in some parts of the country.
• We have to balance the need to have the best possible safeguards against the risk that delay will result in additional outbreaks and further spread of disease. The purpose of slaughtering sheep that have been exposed to the risk of infection is to prevent the establishment of new disease foci. This suggests that speedy action with reasonable safeguards is preferable to slower action with better safeguards.

3. RECOMMENDED ACTION

On the basis set out above, the following are recommended as reasonable options for destroying sheep on premises which are subject to Form D restrictions because animals there have been exposed to the risk of infection. Variations may be justifiable if circumstances change, the guiding principle being that where the choice is between two risks, the lower risk action should be selected. Thus an action which may reasonably be taken in one area would be quite inappropriate in another. Section E (below) applies this principle in respect of a specific geographical area.

1. Veterinary inspection of all susceptible livestock
2. Destroy sheep on farm
3. Send carcases to be rendered (preferable) or landfilled (possible) at a site in a higher risk Controlled Area or in an Infected Area.

1. As A, i-iii.
2. Alternatively, licence to slaughterhouse in higher risk Controlled Area or Infected Area, to be slaughtered within 24 hours of arrival.
3. All susceptible livestock on farm to be inspected by a veterinary surgeon for evidence of FMD immediately before loading the sheep.
4. Movement from farm to slaughterhouse to be as direct and short as reasonably possible.
5. No movement into or through lower risk Controlled Areas.

1. As A, i-iii.
2. Alternatively, licence to slaughterhouse in the same Infected Area to be slaughtered within 24 hours of arrival.
3. All susceptible livestock on farm to be inspected by a veterinary surgeon for evidence of FMD before sheep are loaded.
4. Movement from farm to slaughterhouse to be as direct and short as possible.
5. Movement to take place entirely within the Infected Area.

1. As A i-iii.

1. The weight of infection and pressure on disposal facilities in this area justifies action that carries a greater risk than would be acceptable elsewhere. The risk of transmission as a result of following these recommendations is much less than the risk of transmission if the slaughter of infected or potentially infected animals were to be delayed.
2. Within this area, sheep may be:
   • slaughtered on farm, the carcases being cremated there or moved under licence to be buried on a licensed tip, cremated at a central site within the area, or to a rendering plant.
   • moved to a slaughterhouse within the pre-emptive slaughter area for immediate slaughter
   • moved to a centralised slaughter site, such as market premises within the pre-emptive slaughter area, to be killed there and the carcases then licensed to another site for burial or cremation

No veterinary inspection would be carried out on the farms, but animals that were sent to a slaughterhouse would be subject to veterinary ante-mortem inspection there.

Whenever Form D premises are depopulated of sheep it is advisable that sufficient blood samples are collected at the time of slaughter to gain 95% confidence of detecting a 5% prevalence of infection in the slaughtered flock.

Contributors:

Dr A Donaldson IAH Pirbright Laboratory
Dr T England Risk Research Dept, VLA
L Gallagher Risk Research Dept, VLA
Dr L Kelly Risk Research Dept, VLA
Dr P Kitching IAH Pirbright Laboratory
R Jones Risk Research Dept, VLA
C Livesey Risk Research Dept, VLA
Dr M Wooldridge Head of Risk Research Dept, VLA, Weybridge

23^rd March 2001